How do I check for chlorine in RO system

[Indiana Wash]

OK, I have seen several discussions about RO maintenance. Mine has not been maintained and I am doing a full maintenance. I suspect that my charcoal needs replaced. I have changed the prefilter and have the membranes on order. I am just worried about the charcoal filter. It has not been serviced for some time. I saw MEP's post that said to check the reject water for chlorine. How do I do that? How many ppm should be there? None? Can I use a pool test kit? Thanks.

 

[MEP001]

Yes, you can use a pool test kit. I test the RO reject because it concentrates the chlorine, which depending on your city may not have enough to even show up with a regular pool/spa kit.

I have always replaced the charcoal with the membranes. It's not a big cost for the assurance it gives.

 

[Indiana Wash]

Ok, so I think I have a crane like kr sells. Do I just unscrew the top, dump and refill????

 

[MEP001]

There's probably a bed of filter gravel at the bottom. If you post the dimensions of the tank I can tell you how much it holds.

 

[Jeff_L]

I usually replace in this order:

Charcoal
Wait a few days, depending on how busy I've been
Filter between charcoal and membrane
Wait a few days, depending on how busy I've been
Membrane

My reasoning is I don't want to send anything downstream to the membrane. Basically, washing everything out and letting the old components get dirtied up.

 

[Indiana Wash]

Ok, I can calculate the volume of a cylinder and KR sells activated carbon by the cubic foot. When I go to tear this thing apart, is there gravel at the bottom that I will need or is it dump and replace???

 

[MEP001]

I've serviced many RO systems and never took as much care as Jeff_L does, but it's not a bad idea to wait between changing the items like he described. The prefilter will turn black no matter how well you flush the carbon filter before returning it to service.

There is probably filter gravel at the bottom, but I've serviced some that didn't have any. It won't hurt to use it even if it's not there now, and it's cheap.

You don't want to fill the unit to the top. It should be no more than 3/4 full especially if it has a backflush head.

 

[Jeff_L]

I do it that way because that membrane is so darn expensive. So any risk of damaging it I can reduce I will. Lol

 

[mac]

I have an electronic chlorine tester made by Extech Instruments, mainly because I just don't trust the pool test kits. It was a little pricy, around b$300, but since we do this a lot it was worth it. It gives an amazingly accurate number. I test water before the charcoal filter and then downstream and look for the reduction in chlorine of at least 90%. My customers seem impressed with a real meter rather than a pool kit. And remember, the pool places want you to think something is wrong so you'll buy stuff from them. Just my thoughts.